1. Field of the Invention
The invention relates to a pipe clamp for either rams or blocks for removal, working with vibrations.
2. Description of the Related Art
It is known to ram or remove foundation pipes into or from a waterbed in a more or less straight up position by means of a vibrator block placed on the upper end of the pipe. Such pipes are used to secure a structure to the waterbed. To that end the structure, for instance a so-called xe2x80x9ctemplatexe2x80x9d, a xe2x80x9cjacketxe2x80x9d or a xe2x80x9cframexe2x80x9d is provided at the corners with guide bushes for the foundation pipes which can be accommodated in there more or less fitting. With the help of a vibrator block each pipe is forced into the bed through the guide bush concerned and attached to the guide bush, with its upper end.
Known vibrator blocks are provided at their lower ends with at least two pairs of hydraulic operable clamping jaws which always clamp the upper end of the pipe wall between them at opposite locations. The clamping jaws engaging the outer side of the pipe result in a local enlargement of the diameter of the assembly pipe-clamp, as a result of which the pipe cannot entirely be lowered into the guide bush with its upper end.
However, it is often a requirement that the pipes have their upper ends flush with the upper edge of the guiding bushes concerned, so that the protruding upper portions of the pipes have to be cut off. For that purpose a special tool has to be lowered or divers have to be used, which entails high costs.
It is, an object of the invention to improve on this and to that end, from one aspect, provides a device for transferring a vibrating movement to a rigid pipe for letting it penetrate into or removing it from a bed in upright position, comprising clamping means for clampingly holding the upper end of the pipe for transfer of the vibrating movements thereto and biassing means for the clamping means, which clamping means comprise at least two clamping members that can be biassed away from each other by means of the biassing means, for clampingly engaging the -particularly opposite- inner surfaces of the pipe.
Because the pipe wall itself provides the counter clamping force and the pipe is exclusively engaged onxe2x80x94particularly oppositexe2x80x94inner surfaces, no clamping members that extend outside of the pipe wall are present. As a result the pipe can be rammed entirely into the guide bush, without the follow-up treatment of cutting off the upper end being necessary.
In a further development of the device according to the invention it comprises a body with means for attachment to a vibrator block, the clamping members forming a rigid unity with the body in pipe direction. The vibration forces (alternatingly upwards and downwards) are transferred here from the vibrator block, via the clamping members, to the pipe according to a direct force path.
Preferably the clamping means comprise one or more wedge members that can be moved in the direction of the pipe by the biassing means, which wedge members under tension press the clamping means radially outwards.
For reasons of constructive simplicity it is preferred if there is one central wedge member, which is active to several sides.
According to a further development the wedge members are provided with at least one wedge plane, of which the normal has a directional component in the direction towards the lower end of the pipe. Considered from another aspect the biassing means are active to move the wedge members in downward direction for biassing the clamping members. In this way the biassing means can be active from above and room is provided to the wedge members and the clamping members, so that they can be designed strong enough for nearly all purposes.
It is preferred here that the biassing means comprise a cylinder/piston assembly, the piston being situated above the clamping means, so that the space next to the clamping members is entirely available to the wedge members. If the device is further provided with a stop plate for the upper end of the pipe, it is preferred that the piston is situated above the stop plate. Furthermore also the cylinder of the cylinder/piston assembly is preferably situated entirely above the clamping means.
A further simplified construction and reliable working is realized when the piston rod of the cylinder/piston assembly is directly attached to the wedge members at the end which faces away from the piston.
The taking up of space in radial direction is kept small according to a further development of the device according to the invention when the wedge members are provided with a series of wedge planes which are arranged saw-toothed in the pipe direction. The taking up of space in radial direction here can even be independent from the engagement length of the clamping members in the pipe direction.
This saved space can for instance be used for making the clamping members two-pieced, the clamping members being assembled from an inner clamping part, which for wedge activity abuts the wedge member concerned, and an outer clamping part, which is detachably arranged on the inner clamping member. Thus the device can be used for various very different pipe diameters, by changing the outer clamping members.
According to a further development the wedge member and the clamping member are connected to each other by means of a pin/slit connection, the slit extending in pipe direction. In this way the wedge member can slide in pipe direction with respect to the clamping member.
It is noted that from CH-A-400.023 a device is known for transferring forces to a pipe for letting it penetrate in a bed or removing it from it. This device comprises clamping means with a wall with filling pieces extending over the pipe and a centrally situated wedge member and further wedge members intended to engage the inner surface of the pipe attached around it extending within the pipe. In use fluid under pressure is supplied in order to force a piston which is operatively connected to the central wedge member, upwards and therewith force the further wedge members against the inner surface of the pipe. The intention here is to deform the pipe outwardly at that location so that it will closely abut the wall and/or filling pieces extending over the pipe.
From a further aspect the invention relates to an assembly of a device according to the invention and a vibrating block.
From yet another aspect the invention provides a method for transferring a vibrating movement on a rigid pipe for letting it penetrate into or removing it from a bed in upright position, the clamping means of the assembly according to the invention being inserted in the upper end of the pipe, the biassing means being activated to let the clamping means clampingly engage the inner surfaces of the pipe and keeping them clamped, without noticeable deformation of the circumference of the pipe at that location, and subsequently activating the vibrator block.
Preferably exclusively those circumferential surfaces of the pipe are clampingly engaged, which are situated on the inside of the pipe.